1. Field of the Invention
The present invention relates to a resin composition, a resin cured product and a liquid discharge head.
2. Related Background Art
An epoxy resin composition is capable of providing a cured product having excellent heat resistance, adhesiveness, electrical insulating properties, and the like, and thus is preferably used in applications such as a semiconductor sealer, a printed wiring board, paint, and a casting material. Of those, in electrical and electronic applications requiring particularly high reliability, use of an epoxy resin (hereinafter, referred to as an epoxy resin (A)) represented by Formula (1) described below and having a dicyclopentadiene skeleton is proposed. The epoxy resin (A) has a bulky cyclic aliphatic hydrocarbon skeleton in a molecule and thus has properties of low water absorption property and low dielectric constant:
where: R represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a t-butyl group; n represents an integer of 0 to 4; and m represents an integer of 1 to 3.
Meanwhile, a photocuring technique involving cationic ring opening polymerization of an epoxy resin with a cationic UV-curable initiator (photocationic polymerization initiator) is in practical use in wide ranging fields such as coating agent, ink, a resist for producing a semiconductor, and a stereo lithography resin.
In recent years, there is known a method of producing a liquid discharge head for forming a liquid passage by applying the photocuring technique and subjecting a photocationic curable resin layer laminated on a substrate to photolithography techniques such as exposure and development. For example, Japanese Patent Application Laid-Open No. H03-184868 discloses a method of forming a liquid passage by subjecting an epoxy resin having a bisphenol-A, F, or S skeleton or an o-cresol novolac-type epoxy resin to photocationic polymerization.
A known application example of the liquid discharge head is an ink jet recording head in which the head is loaded in a recording device. At present, a commercially available ink jet recording head has a high ink jet discharge port density of 600 dpi and requires a technique of producing a fine ink passage.
Therefore, the method of forming a passage for an ink jet recording head applying photolithography techniques and described above is better than conventionally known methods employing plating and laser processing in view of precision in forming a desired passage and discharge port pattern.
Meanwhile, a passage wall forming member of an ink jet recording head is constantly in contact with ink during use of a product. Generally used ink is often alkaline and contains an organic solvent. Low water absorption property and excellent solvent resistance are strongly desired for the passage wall forming member constantly in contact with such a substance. In the case where the passage wall forming member has no such properties, the passage wall forming member undergoes volume swelling and the passage or the discharge port deforms. Thus, a desired discharge state may not be obtained, and the passage wall forming member may peel off from the substrate.